Using tracer-aided ecohydrological models to assess the impact of alternative land use strategies on optimizing water availability in drought-sensitive catchments
- 1Geography Institute, Humboldt University of Berlin, Berlin, Germany
- 2IGB Leibniz-Institute of Freshwater Ecology and Inland Fisheries Berlin, Berlin, Germany
- 3Northern Rivers Institute, School of Geosciences, University of Aberdeen, Aberdeen, UK
Recent consecutive drought years have led to multiple negative impacts on water-related ecosystem services in many parts of the world; these include reduced crop yields, increased tree mortality, persistent soil moisture deficits, lower groundwater levels and stream flow becoming more intermittent. Continuing negative rainfall anomalies, coupled with climate change projections of increased drought severity and frequency, drive an urgent need to increase resilience and integration in land and water management strategies. However, complex interactions between land cover change, hydrological partitioning and water availability are difficult to quantify, especially at different temporal and spatial scales. Process-based ecohydrological modeling, particularly when calibrated with multiple data streams, is a powerful tool for estimating water partitioning and assessing the impact of alternative land management strategies on catchment water resources. We employed the spatially-distributed and tracer-aided ecohydrological model, EcH2O-iso, to quantify the effects of current and potential future land use scenarios on ecohydrological water flux partitioning and water ages in a 66 km2 drought-sensitive catchment in the North European Plain, Germany. The model was calibrated using hydrometric, ecohydrological and isotopic data at daily time steps for a period of 13 years (Jan 2007 – Dec 2019). In conjunction with local stakeholders, we developed plausible, alternative land-use scenarios (including forest diversification and agroforestry schemes) based on the existing four primary land-use types (i.e., broad-leaved forests, conifer forests, arable agriculture and pasture) to evaluate spatial and temporal changes to water flux partitioning and water ages. This sought to identify the most drought-resilient land management plan especially in the context of increased drought frequency and severity. The results showed that replacing conifer forests with uneven-aged mixed forests with younger broad-leaved trees had the most positive impacts in terms of reducing total evapotranspiration and increasing groundwater recharge in the catchment. The mixed-forest management alternatives also significantly reduced groundwater ages and subsurface water turnover times. This indicates that under this management soil moisture and groundwater stores will recover more quickly from drought than under existing land management. This study demonstrates an ecohydrological modelling approach that provides importance science-based evidence for policy makers allowing quantitative assessment of the impact of different land-use types on water partitioning and water availability. Other current work is coupling the tracer-aided ecohydrological model with a nitrate model for future assessment of biogeochemical processes.
Keywords: ecohydrological modeling; drought-sensitive area; water partitioning; water age
How to cite: Luo, S., Tetzlaff, D., Smith, A., and Soulsby, C.: Using tracer-aided ecohydrological models to assess the impact of alternative land use strategies on optimizing water availability in drought-sensitive catchments, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-108, https://doi.org/10.5194/egusphere-egu23-108, 2023.
